AB1332 INSIGHTS INTO DISEASE ACTIVITY SCORE IN 28 JOINTS (DAS28) AND ITS COMPONENTS FROM AN ULTRASOUND PERSPECTIVE AMONG PATIENTS WITH RHEUMATOID ARTHRITIS
Authors: J. Kow, G. H. Lim, Y. K. Tan
Journal: Annals of the Rheumatic Diseases (2022)

Background Disease Activity Score in 28 Joints (DAS28) is a composite disease activity score commonly used to evaluate disease activity in rheumatoid arthritis (RA). Musculoskeletal ultrasound (US) allows visualization and assessment of joint inflammation and structural damage in RA. Objectives The aim of this study is to gain insights into DAS28 and its components through studying their relationship with US detected joint inflammation and bone erosion (BE). Methods At each joint recess, US power Doppler (PD) and greyscale (GS) joint inflammation were semi-quantitatively (0 to 3) graded using validated scoring methods while BE was scored as present=1 or absent=0 based on Outcome Measures in Rheumatology (OMERACT) consensus definition of BE. At the patient level, Pearson’s correlation coefficient was used to correlate US PD, GS and Erosion scores with the following clinical variables: DAS28 and its components (including the erythrocyte sedimentation rate (ESR) in mm/hr; swollen joint count (SJC) ranging from 0 to 28; tender joint count (TJC) ranging from 0 to 28; and patient’s global assessment (PGA) of disease activity ranging from 0 to 100). Bonferroni correction was used to account for the above multiple testing. Among associations which were statistically significant, simple linear regression was used to describe the relationship between variables. Results A total of 2520 joints and 2800 joint recesses from 36 joint sites (bilateral proximal interphalangeal joints, thumb interphalangeal joints, metacarpophalangeal joints, metatarsophalangeal joints, wrists, elbows and ankles) were scanned in 70 adult RA patients (baseline characteristics: 81.4% female; 74.3% Chinese; mean (SD) DAS28 3.99 (1.25); mean (SD) disease duration 75.3 (61.2) months). All 70 patients underwent US joint inflammation assessment with a subset of 30 patients assessed for US BE. Table 1 summarizes the correlation results between the US and clinical variables. US PD scores were correlated with DAS28 (r=0.34, p=0.02) and SJC (r=0.33, p=0.03). US GS scores were correlated with DAS28 (r=0.42, P=0.002). US Erosion scores were correlated with SJC (r=0.69, P&lt;0.001). Simple linear regression (see scatter plots in Figure 1) demonstrated a statistically significant relationship between the following variables: US PD score versus DAS28 (R 2 =0.13, p=0.004); US PD score versus SJC (R 2 =0.11, p=0.008); US GS score versus DAS28 (R 2 =0.18, P&lt;0.001); US Erosion score versus SJC (R 2 =0.48, p&lt;0.001). Table 1. Pearson’s correlation between the ultrasound and clinical variables DAS28 ESR (mm/hr) Swollen Joint Count (0-28) TenderJoint Count (0-28) Patient’s Global Assessment (0-100) r 2 p-value r 2 p-value r 2 p-value r 2 p-value r 2 p-value US PD score 0.34 0.02* 0.29 0.08 0.33 0.03* 0.15 &gt;0.99 0.16 &gt;0.99 US GS score 0.42 0.002** 0.24 0.20 0.30 0.053 0.29 0.07 0.23 0.30 US Erosion score 1 0.22 0.25 0.14 0.46 0.69 &lt;0.001*** 0.066 0.73 -0.11 0.55 1 Based on subset of 30 patients. 2 Accounted for multiple testing. Statistically significant: *p&lt;0.05; **p&lt;0.01; ***p&lt;0.001 Conclusion Both DAS28 and SJC have significant correlation with US detected joint inflammation. However, among the clinical variables, only SJC appears to be associated with structural damage and has significant correlation with US detected BE. Therefore, it appears that the results from both DAS28 and SJC can be more reflective of the RA disease status when compared to DAS28 alone. The role(s) of both DAS28 and SJC versus DAS28 alone as patient outcome measures in RA need to be further explored. Disclosure of Interests None declared